functional-try
v3.0.0
Published
Error handling wrapper for cleaner use of strict type checking in TypeScript
Downloads
25
Maintainers
Readme
functional-try
Error handling wrapper for cleaner use of strict type checking in TypeScript
This library is intended to replace await-to-js
in projects using TypeScript with strict
settings.
Install
npm i functional-try
Motivation
I use await-to-js
quite extensively in TypeScript projects, with a pattern similar to:
const [err, res] = await to(someAsyncFunction(params));
if (err) {
handleError(err);
return;
}
doSomethingWithRes(res);
But this doesn't work well with strict typing. Even though the return type of to
indicates that err
and res
should be mutually exclusive, TypeScript still thinks res
is possibly undefined
due to the deconstruction severing the logical connection between the two.
This can be avoided by just not deconstucting:
const asyncRes = await to(someAsyncFunction(params));
if (asyncRes[0]) {
handleError(asyncRes[0]);
return;
}
handleSuccess(asyncRes[1]);
In this case TypeScript knows that by the time handleSuccess
is called asyncRes[1]
has a value because asyncRes[0]
doesn't, avoiding the type error. But this doesn't result in very readable code.
This package functions nearly identical to await-to-js
, just returning an object instead of a tuple, making usage without deconstruction cleaner.
Usage
Import
import { trySync, tryAsync } from 'functional-try';
Synchronous
trySync
takes a function and the parameters to invoke it with. It will synchronously call the function, automatically catch any errors, and return an object containing the function's result or caught error.
const parsedJson = trySync(JSON.parse, fileString);
if (!parsedJson.success) {
console.log('Error parsing JSON', parsedJson.error);
return;
}
handleSuccess(parsedJson.value);
Asynchronous
tryAsync
takes a promise and returns another promise that resolves to an object containing the first's result or caught error.
const asyncRes = await tryAsync(someAsyncFunction(params));
if (!asyncRes.success) {
handleError(asyncRes.error);
return;
}
handleSuccess(apiRes.value);